1. Field of the Invention
This invention pertains generally to electronic spray deposition sensors, and more particularly to electronic spray deposition sensors having a sensor array.
2. Description of Related Art
There has been considerable previous research on spray deposition assessments for agricultural sprayers. Historically, spray deposition studies have relied on the use of water and oil sensitive paper to document deposition rates. This technique requires the placement, collection, scanning and post processing of stains on cards, and is time consuming and labor intensive.
However, the need to easily and accurately estimate spray efficiency, penetration of spray through a foliar canopy and uniformity of deposition over crop surfaces persists. Often, such as in worker exposure, pesticide residue assessments and efficacy studies, spray deposition must be quantified as mass of active ingredient per unit target area or mass. For these applications, the chemical or a tracer, such as a fluorescent tag, must be extracted from the target substrate or removed from the surface, then the solvent analyzed for the active ingredient. These chemical analyses can be costly and subject to errors from contamination and recovery problems. Moreover, they cannot always provide information on spatial distribution of deposition, droplet deposition density or the fraction of target area covered by the deposit.
An alternative to chemical analysis for quantifying spray deposition is the optical measurement of visual spray deposition. Such analysis can provide information on size spectra of droplet deposits, spatial uniformity of deposition and extent of deposition coverage. Optical contrast between spray deposit and target substrate can be achieved by addition of dyes and fluorescent tracers in the spray or use of a water sensitive paper (WSP) that reacts to deposition to form stains [Fox et al. (Fox, R. D., M. Salyani, J. A. Cooper and R. D. Brazee. 2001: Spot size comparisons on oil and water sensitive paper. Applied Eng. Agric. 17(2): 131-136), Giles and Downey (Giles, D. K. and Downey, D. 2003. Quality control verification and mapping for chemical application. Prec. Agric. 4:103-124), Wolf (Wolf, R. E. 2003. Assessing the ability of Dropletscan to analyze spray droplets from a ground operated sprayer. Applied Eng. Agric. 19(5):525-530), Womac et al. (Womac, A. R., C. W. Smith and J. E. Mulrooney. 2004. Foliar spray banding characteristics. Trans. ASAE 47(1):37-44)].
Use of water sensitive paper or other optical techniques for deposition studies involves setting, numbering, collecting, and post processing data manually, with image processing technology. The process is a tedious, meticulous and time-consuming task. An additional limitation of these techniques is that they do not provide real-time measurements. The target substrates, either plant material such as leaves, or artificial targets must be removed and analyzed, often days or weeks after the spray application.
A number of different sensor types have been used for spray deposition and for characterizing wetness patterns in agricultural production systems, such as greenhouses, including radiometric sensors [Stonehouse (Stonehouse, J. M. 1990. A camera mount for the photography of spray tracer deposits in the field. J. Agric. Eng. Res. 47:207-211), Babcock et al. (Babcock, J. M., J. J. Brown and L. K. Tanigoshi. 1990. Volume and coverage estimation of spray deposition using amino nitrogen calorimetric reaction. J. Econ. Entomology 83(4):1633-1635)], artificial surface sensors [Weiss et al. (Weiss, A., D. L. Lukens and J. R. Steadman. 1988. A sensor for the direct measurement of leaf wetness: Construction techniques and testing under controlled conditions*1. Agric. & Forest Meteorology, 43 (3-4), 241-249), Giesler et al. (Giesler, L. J., G. L. Horst and G. Y. Yuen. 1996. A site-specific sensor for measuring leaf wetness duration within turfgrass canopies. Agric. & Forest Meteorology, 81 (1-2), 145-156), Davis and Hughes (Davis and Hughes. 1970. A new approach to recording the wetting parameter by use of electrical resistance sensors. Plant Disease Reporter, 54:373-479)], and electronic (resistance) sensors [Miranda et al. (Miranda, R. A. C., T. D. Davies and Sarah E. Cornell. 2000. A laboratory assessment of wetness sensors for leaf, fruit and trunk surfaces. Agric. & Forest Meteorology, 102 (4), 263-274)]. Sensors give variable non-linear responses depending on the distribution and quantity of moisture present.
Even with the considerable research that has been documented to characterize spray deposition patterns from different sprayers and for different commodities, often times the spray effects are site or research technique specific, as analysis of WSP becomes subjective for the specific laboratory, and the scanning procedure is unique to the lab doing the spray deposition research. There are no developed standards for WSP analysis and many of the new developments continue to be essentially manual operations.
Accordingly, it is an object of the present invention to provide reusable, electronic liquid deposition sensor with automated data recovery.
A further object of the present invention is a real-time spray sensor to quantify and localize spray deposition in situ for agricultural spraying.
Another object of the present invention is an electronic deposition sensor that is capable of transmitting data, via a wireless network, to a local site or external receiver mounted in a mobile vehicle.
Yet a further object of the present invention is an electronic deposition sensor that calculates a grid pattern of the spray deposition within an entire field. At least some of these objectives will be met in the following description.